A little confused about this purchase agreement contract

[Jeff Ashachik]

So I downloaded a purchase agreement from the BiggerPockets File Place but I have a question about the pricing section, this is what it looks like:

SALE PRICE:                $_______

SUBJECT TO: ______  $_______

EQUITY:                       $_______

What do the "subject to" and "equity" lines mean and what needs to go there? Why isn't "sale price" enough?

thanks!